全文获取类型
收费全文 | 22140篇 |
免费 | 3847篇 |
国内免费 | 2081篇 |
专业分类
电工技术 | 3042篇 |
技术理论 | 1篇 |
综合类 | 2008篇 |
化学工业 | 3465篇 |
金属工艺 | 618篇 |
机械仪表 | 1685篇 |
建筑科学 | 438篇 |
矿业工程 | 297篇 |
能源动力 | 936篇 |
轻工业 | 880篇 |
水利工程 | 250篇 |
石油天然气 | 903篇 |
武器工业 | 419篇 |
无线电 | 3271篇 |
一般工业技术 | 3316篇 |
冶金工业 | 414篇 |
原子能技术 | 392篇 |
自动化技术 | 5733篇 |
出版年
2024年 | 111篇 |
2023年 | 531篇 |
2022年 | 841篇 |
2021年 | 919篇 |
2020年 | 1110篇 |
2019年 | 971篇 |
2018年 | 979篇 |
2017年 | 1152篇 |
2016年 | 1257篇 |
2015年 | 1280篇 |
2014年 | 1552篇 |
2013年 | 1699篇 |
2012年 | 1735篇 |
2011年 | 1834篇 |
2010年 | 1200篇 |
2009年 | 1283篇 |
2008年 | 1153篇 |
2007年 | 1310篇 |
2006年 | 1114篇 |
2005年 | 871篇 |
2004年 | 747篇 |
2003年 | 692篇 |
2002年 | 542篇 |
2001年 | 436篇 |
2000年 | 465篇 |
1999年 | 325篇 |
1998年 | 304篇 |
1997年 | 283篇 |
1996年 | 241篇 |
1995年 | 180篇 |
1994年 | 181篇 |
1993年 | 113篇 |
1992年 | 118篇 |
1991年 | 111篇 |
1990年 | 79篇 |
1989年 | 58篇 |
1988年 | 39篇 |
1987年 | 42篇 |
1986年 | 30篇 |
1985年 | 35篇 |
1984年 | 40篇 |
1983年 | 30篇 |
1982年 | 41篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1974年 | 2篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
A localized surface plasmon resonance based immunosensor for the detection of casein in milk 总被引:2,自引:0,他引:2
Ha Minh Hiep Kagan Kerman Do-Kyun Kim Yuzuru Takamura 《Science and Technology of Advanced Materials》2007,8(4):331-338
In this research, a localized surface plasmon resonance (LSPR) immunosensor based on gold-capped nanoparticle substrate for detecting casein, one of the most potent allergens in milk, was developed. The fabrication of the gold-capped nanoparticle substrate involved a surface-modified silica nanoparticle layer (core) on the slide glass substrate between bottom and top gold layers (shell). The absorbance peak of the gold-capped nanoparticle substrate was observed at ∼520 nm. In addition, the atomic force microscopy (AFM) images demonstrated that the nanoparticles formed a monolayer on the slide glass. After immobilizing anti-casein antibody on the surface, our device, casein immunosensor, could be applied easily for the detection of casein in the raw milk sample without a difficult pretreatment. Under the optimum conditions, the detection limit of the casein immunosensor was determined as 10 ng/mL. Our device brings several advantages to the existing LSPR-based biosensors with its easy fabrication, simple handling, low-cost, and high sensitivity. 相似文献
122.
Evaggelia D. Tzika Vassiliki Papadimitriou Theodore G. Sotiroudis Aristotelis Xenakis 《European Journal of Lipid Science and Technology》2008,110(2):149-157
The autoxidation at alkaline pH and enzymatic oxidation by mushroom tyrosinase of oleuropein, the dominant biophenol present in the fruits and leaves of Olea europea, was followed by both electron paramagnetic resonance (EPR) and absorption spectroscopy. For comparison, the same oxidation processes were applied to 4‐methylcatechol, a simple polyphenol present in olive mill wastewaters. EPR spectra of stable o‐semiquinone radicals produced during autoxidation at pH 12 and short‐lived o‐semiquinone free radicals produced during autoxidation at pH 9.0 or tyrosinase action and stabilized by chelation with a diamagnetic metal ion (Mg2+) were recorded for both polyphenols, and the corresponding hyperfine splitting constants were determined. The UV‐Vis spectral characteristics of the oxidation of polyphenols were highly dependent on the type of polyphenol, oxidant type and the pH of the reaction. The kinetic behavior of tyrosinase in the presence of oleuropein and 4‐methylcatechol was followed by recording spectral changes at 400 nm (absorption maximum) over time. The tysosinase activity with oleuropein showed a pronounced pH optimum at pH 6.5 and a minor one around pH 8. From the data analysis of the initial rate at pH 6.5, the kinetic parameters Km = 0.34 ± 0.03 mM and Vmax = 0.029 ± 0.002 ΔA400 min–1 were determined for oleuropein. 相似文献
123.
The temperature programmed (palladium) hydride decomposition appeared very effective method for diagnosing the extent of alloying in Pd-Pt/SiO2 catalysts. Introduction of Pt to Pd catalysts moves the TPHD peak gradually towards lower temperatures and the shift in hydride decomposition peak is accompanied by a decrease in the amount of released hydrogen. The catalysts prepared the direct redox method showed much better alloy homogeneity than the samples prepared by coimpregnation. The results of probing with other techniques, i.e. catalytic probing with hydrodechlorination of CCl2F2 and XRD, were in line with TPHD data. The catalytic probing showed the presence of synergistic effect, a clear indication of Pd-Pt mixing. XRD data of post-reaction samples showed carbon incorporation into Pd-rich phase, whereas separate Pt-rich phase did not experience any bulk carbiding. 相似文献
124.
125.
本文研究了用金属有机物热发解法制备PLT8薄膜的工艺过程和基片对薄膜结构的影响,并且给出了铁电性能的测量结果。 相似文献
126.
A new synthesis procedure for titanium-containing aluminosilicate zeolites has been obtained using a clear colloidal dispersion (sol) which was prepared with titanium isopropoxide, water, hydrochloric acid and colloidal silica, Ludox. When NaY, KL, offretite, mordenite and ZSM-5 zeolites were crystallized from the sol following conventional hydrothermal crystallization procedures, all the aluminosilicate zeolites showed the same X-ray absorption fine structure at the Ti K edge indicating framework Ti. The zeolites showed remarkable catalytic activity for the partial oxidation of cyclohexene using H2O2 as an oxidant and the photocatalytic decomposition of trichloroethene using water. 相似文献
127.
采用奇异值分解设计广义系统的最优滤波器 总被引:6,自引:2,他引:4
本文讨论广义离散随机线性系统的状态估计问题,通过矩阵奇值分解,本文给出了一种设计降阶最优滤波器的实用方法,该方法同时还得到了动态系统和量测系统的干扰噪声的估计。 相似文献
128.
激光与DNA作用系统的随机共振研究 总被引:6,自引:2,他引:4
建立了激光与DNA分子系统相互作用的Fokker-Planck方程,通过对该方程的数值研究,发现在绝热近似下,系统发生随机共振,噪声强度,激光振幅和频率协同作用共同制约着生物系统的演化过程,噪声强度在生物系统遗传变异过程中可能起重要作用。 相似文献
129.
The decomposition of NO and of N2O over a CuZSM-5 zeolite and a Fe-mordenite, respectively, has been studied using tracer techniques. The results demonstrate the high mobility of the lattice oxygen ions in self-diffusion. They afford a possible explanation for the problem of how two extralattice oxygens located at positions remote from each other may combine to form the O2 molecules which are spontaneously desorbed in these redox reactions. They show that a portion of the lattice oxygen mixes into the O2 released on decomposition. The data also show that N18O and N2
18O undergo exchange with the catalyst oxygen under reaction conditions.On leave from Central Research Institute for Chemistry, Hungarian Academy of Sciences, H-1525 Budapest, Hungary. 相似文献
130.